Sewing machine for sewing covering strips



Jan. 31, 1967 K. F. NAGELE SEWING MACHINE FOR SEWING COVERING STRIPS Filed Sept. 15, 1964 United States Patent 3,301,203 SEWING MACHINE FOR SEWING COVERING STRIPS Karl Friedrich Niigele, Osumstrasse, Stuttgart- Hohenheim, Germany Filed Sept. 15, 1964, Ser. No. 396,612 Claims priority,'application Germany, Sept. 21, 1963,

6 Claims. (Cl. 112-2) This invention relates to a sewing machine for sewing covering strips on one or both sides of the locking members of a slide fastener half wherein the locking members are interconnected by a carrier ribbon or stringer tape.

In the art of. slide fasteners it is required for various purposes or in dependence on the material of the locking members, that the locking members, consisting of metal or plastic material which may be clamped or injection molded individually on the carrier ribbon, or which may consist of-a plastic material thread wound either helically or bent as a U-shaped meander connected to the carrier ribbon, must be covered on one or both sides to either provide a covered or invisible closure and/or a protection against the heat of ironing. To this end the covering is applied by sewing narrow strips or hands thereon which may either be connected with the carrier ribbon or are fed to the sewing machine separately. It is of importance when applying the covering strips that the stitches of the sewing needle are located exactly between two adjacent locking members so as to avoid breakage of the needle if metal locking members are used, or to avoid longitudinal displacement of the locking members resulting in uneven spacings of the locking members. Practice has shown that the feed mechanism or fabric advancer of common sewing machines does not operate with sufiicient precision to prevent the above mentioned drawbacks.

'It is an object of this invention to provide means assuring that the sewing machine needle is guided with absolute safety through the interstices between successive locking members when covering strips are sewed onto the sides of a carrier ribbon having the locking member connected thereto. According to the invention, this is accomplished by relatively simple means in which commonly used transporters or fabric advancers are omitted.

Accordingly the invention is characterized by the fact that the sewing machine comprises a cylindrical conveyor screw rotatably supported with its axis parallel to the sewing direction and driven in synchronism with the sewing machine, the threads of the conveyor screw having a pitch corresponding to the spacing of the locking members. The individual locking members are provided with coupling surfaces and guided to engage between the threads of the conveyor screw, which is driven to advance the slide fastener half together with the covering strips about one center-to-center spacing of the locking members for each needle stitch. Preferably one or more threads of the conveyor screw are omitted to provide a clear space for the sewing needle so that the operation of the sewing neelde is under no circumstances obstructed. The clear sewing space also makes it possible for a support for the locking members to extend radially into the path of the elements engaging the conveyor screw said support or supports being provided with a bore forming a passage for the needle.

The most advantageous and most exact results may be obtained with simple means if the advance of the lockin-g members is interrupted during the piercing movement of the needle. According to the invention this is achieved in such a manner that the threads of the conveyor screw extend around a major portion, approximately 73, of the circumference without a pitch angle, while the 3,361,203 Patented Jan. 31, 1967 helically pitched portion extends around /3 of the circumference. During the rotation through about /a of each revolution, the conveyor screw holds the slide fastener half stationary so that the needle can make its stitch, whereon the advance of one locking member spacing takes place during the continued rotation of the conveyor screw through about /3 of one revolution.

One embodiment has been shown by way of example in the accompanying drawing, in which FIG. 1 is a fragmentary perspective view of a covered slide fastener half;

FIG. 2 is a top plan view of. the conveyor screw with the slide fastener half guided in a sewing machine;

FIG. 3 is an enlarged fragmentary cross-sectional view taken along line IIIIII of FIG. 2.

For sewing covering strips 1 and 2 for the coupling elements or locking members 3a secured to the carrier ribbon or stringer tape 3 of a slide fastener half on one or both sides thereof a conveyor screw 4 is journalled for example with its ends in antifriction bearings 5 in a sewing machine with its rotational axis parallel to the sewing direction and is driven synchronously by the main drive shaft of the sewing machine via gears 6 and a worm 7 as explained in detail below. The conveyor screw 4 has threads 9 formed thereon which extend approximately about /a of the circumference without a pitch angle and about /3 of the circumference with the full pitch corresponding to the center-to-center spacing of the coupling elements or locking members 3a of the slide fastener half. The helically pitched portion of the threads is designated with the reference numeral 9a.

In the operating zone 10 of the sewing needle 8 the conveyor screw 4 is cut away intermediate its ends so that one or a plurality of threads of the conveyor screw 4 is or are omitted and in this zone 10 the cylinder of the conveyor screw 4 is shown provided with an undercut annular groove to provide a clear sewing space.

A guide 11, 12 for the slide fastener half 3, 3a extends parallel to the conveyor screw 4. The carrier ribbon 3 is guided bewteen the members 11 and 12 with the locking members 3a projecting outwardly beyond the guide members 11 and 12 and between the guide members 13 and 14 in such a manner that the locking members 3a with their coupling surfaces facing the conveyor screw 4 extend between adjacent threads 9 of the conveyor screw in order to advance the slide fastener half progressively through the sewing machine. The lower guide member 14 is extended at 14a into the sewing space provided by zone 10 of the missing threads of the conveyor screw 4 and this extension 14a forms a support for the locking members 3a during the sewing operation. A through bore 15 is provided in the extension 14a allowing the sewing needle 8 to pass freely the-ret-hrough, and in addition the upper guide member 13 facing the conveyor screw has a notch formed therein laterally enclosing the sewing needle 8 whereby this enclosure and the lower bore 15 provide a satisfactory guide for the sewing needle.

The operation is as follows:

The slide fastener half, comprising the carrier ribbon 3, the locking members 3a, which are clamped around the head of the carrier ribbon, and the lateral covering strips 1 and 2 is fed into the sewing machine by the conveyor screw 4 and the sewing machine operates in such a manner that the sewing needle 8 pierces in succession the covering strips 1 and 2 and the bead of the carrier ribbon between two adjacent locking members 3a. The piercing takes place during engagement of locking members 3a by the portion of the screw thread having no pitch, while the slide fastener half is held against Longitudinal displacement. As soon as the needle has completed its stitch, the complete thread pitch part engages the locking members 3a and causes on advance through a distance equal to the center-to-center spacing of the locking members. Thus the needle pierces exactly in the space between two adjacent locking members and can never strike the locking members. Preferably a brake 16 for the ribbon is arranged at the input end of the conveyor screw 4 so as to feed the slide fastener half in a taut manner to the conveyor screw 4-.

According to the illustrated example the covering strip 1 and 2 may be formed by legs of the carrier ribbon 3 but they may also be fed separately of the carrier rib bon from above and below in front of the needle zone. The locking members 4 may be individual locking members of metal or plastic material, but they may also be formed continuously in form of a helical spring, or bent as a U-shaped meander and connected to the carrier ribbon. The connection of these latter locking members, which preferably consist of plastic material may be onesidedly or symmetrically relative to the carrier ribbon 3. In the first mentioned case an additional one-sided covering by one covering strip is required, while in the second mentioned case two covering strips must be sewed on both sides.

While I have shown and described what 'I believe to be the best embodiment of my invention, it will be apparent to those skilled in the art that various changes and modifications may be made'therein without departing from the spirit and scope of the invention as defined in the appended claims.

What I claim is:

1. A machine for sewing a covering strip to a slide fastener half, said fastener halt comprising a uniformly spaced series of coupling elements fixedly secured along one edge portion of a stringer tape, said machine comprising: sewing means including a needle and means for reciprocating said needle; a conveyor screw member having a helical pitch equal to the center-to-center spacing of said elements and extending past said needle; drive means connected to said sewing means for revolving said screw in synchronism with the reciprocation or said needle; and guide means for receiving said fastener half and said covering strip and presenting said fastener half to said needle with the space between two adjacent ones of said elements positioned for free sewing operation of said needle on said covering strip and said fastener half, said guide means extending parallel to the rotational axis of said screw with outer portions of said elements projecting outwardly therebeyond into the spaces between adjacent threads of said screw.

2. A machine according to claim 1, in which the helical pitch of said screw is substantially zero throughout a major portion of its circumference for holding said tape against longitudinal movement during engagement of said outer portions of said coupling elements with said major portion of said screw circumference, said drive .means synchronizing said revolving of said screw to cause said coupling elements to engage said major portion of said screw circumference during said sewing operation of said needle.

3. A machine according to claim 2, wherein said conveyor screw is cut away intermediate its ends to define a clear sewing space for operation of said needle in the path of travel of said covering strip.

4. A machine according to claim 3, in which "a portion of said guide means projects into said sewing space, said guide means supporting said coupling elements during said sewing operation of said needle. I

5. A machine according to claim 4-, wherein said portion of said guide means which projects into said sewing space has an aperture formed therein tor the tree passage of said needle therethro-ugh.

6. A machine according to claim 3, inwhich the helical pitch of said screw is substantially zero throughout a major portion of its circumference for holding said tape against longitudinal movement during engagement of said outer portions of. said coupling elements with said major portion of said screw circumference, said drive means synchronizing said revolving of said screw to cause said coupling elements to engage said major portion of said screw circumference during said sewing operation of said needle.

References Cited by the Examiner UNITED STATES PATENTS 2,153,006 4/1939 Roseman ll2-2 2,198,345 4/1940 Legat 112 2 3,016,028 1/1962 Schreck etal. 112 2 3,054,364 9/1962 Popovitsch 112 2 3,077,167 2/1963 Morin 112 2 3,135,230 6/1964 Warburton. 112 2 FOREIGN PATENTS 855,084 11/1952 Germany;

JORDAN FRANKLIN, Primary Examiner. 5 J. R. BOLER, Examiner. 

1. A MACHINE FOR SEWING A COVERING STRIP TO A SLIDE FASTENER HALF, SAID FASTENER HALF COMPRISING A UNIFORMLY SPACED SERIES OF COUPLING ELEMENTS FIXEDLY SECURED ALONG ONE EDGE PORTION OF A STRINGER TAPE, SAID MACHINE COMPRISING: SEWING MEANS INCLUDING A NEEDLE AND MEANS FOR RECIPROCATING SAID NEEDLE; A CONVEYOR SCREW MEMBER HAVING A HELICAL PITCH EQUAL TO THE CENTER-TO-CENTER SPACING OF SAID ELEMENTS AND EXTENDING PAST SAID NEEDLE; DRIVE MEANS CONNECTED TO SAID SEWING MEANS FOR REVOLVING SAID SCREW IN SYNCHRONISM WITH THE RECIPROCATION OF SAID NEEDLE; AND GUIDE MEANS FOR RECEIVING SAID FASTENER HALF AND SAID COVERING STRIP AND PRESENTING SAID FASTENER HALF TO SAID NEEDLE WITH THE SPACE BETWEEN TWO ADJACENT ONES OF SAID ELEMENTS POSITIONED FOR FREE SEWING OPERATION OF SAID NEEDLE ON SAID COVERING STRIP AND SAID FASTENER HALF, SAID GUIDE MEANS EXTENDING PARALLEL TO THE ROTATIONAL AXIS OF SAID SCREW WITH OUTER PORTIONS OF SAID ELEMENTS PROJECTING OUTWARDLY THEREBEYOND INTO THE SPACES BETWEEN ADJACENT THREADS OF SAID SCREW. 